JPS639530B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new and useful method for purifying polyphenylene sulfide, and more particularly to a method comprising heat treatment in the presence of an alkylphenyl formaldehyde condensate. Polyphenylene sulfide (hereinafter abbreviated as "PPS") can be melt-molded into engineering plastics, films, fibers, etc. using methods such as injection molding or extrusion. It is widely used in various molded products that take advantage of its chemical properties. As a general method for producing PPS, a method in which an aromatic halide such as p-dichlorobenzene is reacted with sodium sulfide in an organic amide solvent has already been described in Japanese Patent Publication No. 3368/1983.
On the other hand, as an improved polymerization reaction method for obtaining PPS with a high degree of polymerization, Japanese Patent Publication No. 52-12240 also discloses the addition of an alkali metal carboxylate as a polymerization aid. Separately, when such PPS is applied to films, fibers, or various electrical or electronic parts, the salt contained in the polymer must be It is desirable to minimize inorganic electrolyte impurities (also referred to as ash) such as (NaCl). In particular, when the PPS is used as a coating or sealing material for electronic components such as ICs, transistors, or capacitors, parts such as electrodes and wiring of these components may be corroded or disconnected. Inconveniences such as an increase in leakage current occur, but in order to prevent such troubles from occurring, it is absolutely necessary to use a polymer in which electrolyte impurities as described above are reduced as much as possible. By the way, in the case of the PPS manufacturing method as described above, as a result of the fact that almost the same amount of common salt as the produced polymer is produced and precipitated as a by-product, the amount of salt in the polymer that can be obtained only by ordinary processing is unavoidable. contains a considerable amount of residual salt, so it contains a large amount of electrolyte impurities.
Resin compositions obtained using PPS have a drawback in that their electrical properties are significantly inferior to those using a low content of PPS. Therefore, as a measure to eliminate these defects and improve the electrical characteristics, PPS powder obtained through normal processing was repeatedly boiled in deionized water for a long time. and do this
JP-A-55-156342 also describes a method of reducing impurities as much as possible by eluting water-extractable electrolyte components from PPS. However, according to the research conducted by the present inventors, when reducing impurities by the above-mentioned hot water boiling extraction method, it not only takes an unnecessarily long time; The content of electrolyte impurities has also not been reduced as much as expected, and the disadvantage that a polymer with higher purity cannot be obtained no matter how many times or dozens of times the extraction operation is repeated has been eliminated. However, on the other hand, the PPS can be prepared by heating a mixture of PPS and an alkali metal carboxylate or lithium halide in an organic amide solvent, as disclosed in U.S. Pat. No. 4,071,509. Even when methods are tried to reduce the content of inorganic components, PPS purified by any of these methods cannot be used as a coating or sealing material for electronic components. The purity was still not satisfactory. However, as described above, the present inventors
While conducting intensive studies to eliminate the drawbacks of various conventional purification methods and establish a useful purification method, a specific alkyl phenyl formaldehyde condensate was used as a processing component (processing additive) to improve purification efficiency. However, it was discovered that only impurities consisting of electrolyte components containing sodium ions can be removed without any decomposition of the polymer itself, and that the content of such inorganic electrolyte impurities can be efficiently reduced within an extremely short period of time. As a result, we have completed the present invention. That is, the present invention allows impurities consisting of inorganic electrolyte components containing metal ions to be removed in an organic amide solvent.
An extremely effective method that can efficiently reduce the impurity content by removing only the above impurities without decomposing the polymer, which consists of heat treatment in the presence of an alkyl phenyl formaldehyde condensate represented by the following general formula A. The present invention provides a method for obtaining highly pure PPS. General formula A: (In the formula, R ¹ is an alkylene group having 2 to 4 carbon atoms,
R ² is hydrogen or an alkyl group and/or an aryl group having 1 to 30 carbon atoms, and m and n indicate an average degree of polymerization, and represent 2 to 50 and 0 to 90, respectively. ) In carrying out the method of the present invention, the PPS used is MI (melt index) measured according to the method of ASTM D 1238-70.
A sample with a polymer solution concentration of less than 10,000 (g/10 min), i.e., a value measured at a load of 5 kg and a temperature of 315.6°C (600〓), or an intrinsic viscosity of 0.4 g/100 ml, was prepared in α-chlornaphthalene. , 206℃ (403
〓) “Relative viscosity value” based on the measured viscosity
The value obtained by dividing the natural logarithm of by the "polymer concentration", that is, the following formula [η] = ln (relative viscosity value) / polymer concentration [ ], and the value when the polymer concentration is set to infinitesimal, that is, "zero" is greater than or equal to 0.05
PPS is appropriate. In addition, the PPS used in carrying out the method of the present invention is the following formula: The structure with the repeating unit shown is 70
If the mol% or more is preferably 90 mol% or more, it is a product copolymerized with other components, or a part of it has a branched structure, or a part of it has a crosslinked structure. Of course, it can be used even if it is a thing. Typical copolymer components in this case include

Trifunctional units such as [Formula],

Ethe like [formula] etc. unit,

Sulfone units such as [Formula],

Ketones such as [formula] unit,

Meta units such as [formula] or general formulas [However, R in the formula is an alkyl group, phenyl group, alkoxy group, carboxyl group, amino group, sulfone group or nitro group. ] There are substituted sulfide units as shown in the following. Further, in carrying out the method of the present invention, the amount of electrolyte impurities contained in the polymer is arbitrary, and there is no particular restriction on the amount of electrolyte impurities contained in the PPS used, but at least 0.1% by weight, for example, sodium・Those containing ions as electrolyte components. The above-mentioned PPS is the same as the one mentioned above.
It can be produced according to the method of the invention described in Japanese Patent No. 3368 and Japanese Patent No. 52-12240. On the other hand, typical organic amide solvents used in carrying out the method of the present invention include N-methylpyrrolidone, N-ethylpyrrolidone, N,N-
Dimethylformamide, N,N-dimethylacetamide, 2-pyrrolidone, formamide, acetamide, ε-caprolactam, N-methylcaprolactam, tetramethylurea or 1,3-dimethyl-2-imidazolidinone, etc. A mixture of two or more species may be used, and among these, N-methylpyrrolidone is particularly preferred. The amount of the organic amide solvent used is preferably in the range of 1 to 20 parts by weight per 1 part by weight of the above-mentioned PPS. In the method of the present invention, it is necessary to use an alkylphenyl formaldehyde condensate represented by the following general formula A as an additive for separating and removing impurities such as common salt from the PPS polymer. General formula A: (In the formula, R ¹ is an alkylene group having 2 to 4 carbon atoms,
R ² is hydrogen or an alkyl group and/or an aryl group having 1 to 30 carbon atoms; m and n each represent an average degree of polymerization; 2 to 50, preferably 2 to 10; 0 to 90, preferably 3 to 20; represents. ) An example of R ¹ in the above general formula is -CH ₂ CH ₂
--,

[Formula] (-CH ₂ )- ₃ ,

[Formula] (-CH ₂ )- ₄ ,

[However, in the formula, R is a C ₁ to C ₃₀ hydrocarbon group, and X is -COOM and/or -SO ₃ M (here, M is one or more selected from Li, Na, K, Rb and Cs) is an alkali metal), and a is an integer from 1 to 4. ]

There are compounds shown by, among which representative ones are lithium acetate, sodium acetate, sodium benzoate, sodium benzenesulfonate, sodium p-toluenesulfonate,
Sodium α-naphthalene sulfonate, disodium succinate, disodium adipate, disodium phthalate, trisodium sulfophthalate,
These include disodium naphthalene disulfonate and trisodium trimellistate, and these alkali metal salts may be anhydrous salts or hydrates. Furthermore, alkali metal carbonates such as lithium carbonate and sodium carbonate, or alkali metal halides such as lithium chloride and lithium bromide can be used, and they can also be used in combination with the alkali metal salts of the organic acids described above. The amount of the alkali metal salt used is as described above.
0.05 to 4 mol per 100 g of PPS, preferably
A range of 0.1 to 2 moles is appropriate. Note that the method of the present invention can be applied to various PPSs as described above.
In addition to this, it can also be applied to PPS in the form of a blend of various other polymers.
Representative such other polymers include polysulfone, polyether sulfone, polyphenylene oxide, polyetheretherketone, polycarbonate, polyethylene, polyamide, polyester, polyimide or polyether. Thus, in order to purify the PPS according to the method of the present invention, the PPS containing an inorganic electrolyte component consisting of, for example, at least 0.1% by weight of sodium ions and the alkyl The phenyl formaldehyde condensate and, if necessary, the mixture with the alkali metal salt mentioned above, are usually heated at a temperature of 100 to 350°C, preferably 200 to 280°C, for usually 0.1 to 10 hours, preferably 0.5 to 4 hours. It is sufficient to carry out heat treatment while stirring, and through such a treatment operation, the content of sodium ions can be significantly reduced without causing any decrease in the molecular weight of PPS. The pressure within the system at that time may be appropriately selected so as to be within a range sufficient to maintain the organic amide solvent in the liquid phase. The heat-treated mixture is then recovered by conventional procedures, such as by filtering the mixture and subsequently washing the polymer with water, or diluting the mixture with water and washing the polymer with water. be able to. Alternatively, the organic amide solvent can be recovered from the mixture by distillation and/or flashing prior to washing with water. After that, by washing the polymer with water and drying it,
Highly pure PPS can be isolated. Thus, the PPS obtained by the method of the present invention contains almost no impurities consisting of inorganic electrolyte components such as common salt, and has extremely high purity.
It maintains the good electrical insulation properties inherent to PPS. Therefore, PPS obtained by the method of the present invention
PPS can be used not only to obtain various molded products such as films and fibers, but also to obtain molded products such as various electrical or electronic parts.In particular, the PPS obtained by the method of the present invention can be used to obtain molded products such as various electrical or electronic parts. Because it contains almost no electrolyte components that would corrode the electrodes and wiring parts of ICs, transistors,
It is extremely useful as a coating or sealing material not only for individual electronic parts such as diodes, thyristors, coils, varistors, connectors, resistors, and capacitors, but also for electronic parts that are composite parts of these parts. Next, the present invention will be specifically explained using Examples and Comparative Examples. In addition, in the following, the intrinsic viscosity of PPS [η] is
At a polymer solution concentration of 0.4 g/100 ml, α
- Measured in chlornaphthalene at 206°C (400〓) and calculated according to the above formula [], while the sodium ion content in PPS was measured as follows: It is. That is, a polymer is thermally decomposed together with nitric acid in a platinum crucible, and the sodium content in the decomposed liquid is measured by an atomic absorption spectrophotometer using a nitrous oxide-acetylene flame and the flame intensity at a measurement wavelength of 589 nm. Calculate the content of sodium ions in PPS by comparing with a calibration curve created using a commercially available sodium chloride standard solution. Example 1 In a 5 autoclave equipped with a stirrer, 1993 g of N-methylpyrrolidone, 537 g (4.1 mol) of sodium sulfide hexahydrate, and 1.6 g of sodium hydroxide were added.
(0.04 mol) and 144 g (1.0 mol) of sodium benzoate
mol) and gradually raised the temperature to 200℃ under a nitrogen atmosphere with stirring for about 2 hours.
ml of water was distilled off. Next, after cooling the reaction system to 150°C, 603g (4.1 mol) of p-dichlorobenzene and 250g of N-methylpyrrolidone were added, and the reaction was carried out at 230°C for 2 hours and then at 260°C for 3 hours. The internal pressure at the end of the polymerization reaction was 9.0 Kg/cm ² . After that, the autoclave was cooled and the contents were separated, and the cake (solid content) was washed three times with hot water, and twice with acetone, and then washed at 120 ml.
After drying at °C, 412 g of pale gray-brown granular PPS was obtained (yield = 93%). The intrinsic viscosity [η] of the PPS obtained here is 0.27
And the content of sodium ions was 1230 ppm. Next, 20 g of this PPS and a polyoxyethylene nonylphenyl formaldehyde condensate represented by the following formula A (R ¹ = -CH ₂ CH ₂ -, R ₂
=-C ₉ H ₁₉ , average degree of polymerization m = 3 and n = 8)
2.0g and sodium benzoate 26.6g (0.185mol) and N-methylpyrrolidone
200g and 200g were placed in an autoclave equipped with a stirrer, heated under a nitrogen atmosphere, and heated to 265°C while stirring.
Heating was continued for 2 hours, but the internal pressure at the end of heating was
It was 2.8Kg/ ^cm2 . After that, the autoclave was cooled, the contents were separated, and the cake (solid content) was washed three times with hot water and then twice with acetone, and the polymer was recovered. 20 g of polymer was obtained. This polymer had an intrinsic viscosity of 0.29 and a sodium ion content of 12 ppm. As described above, when the method of the present invention is followed, not only is the content of impurities consisting of sodium ions in PPS significantly reduced, but there is no decomposition of the polymer, and the molecular weight is rather increased slightly. The results were approved. Example 2 The same operations as in Example 1 were repeated, except that sodium benzoate was not used in the step of purifying the polymer obtained by polymerization in Example 1.
The final polymer has an intrinsic viscosity of 0.24
The sodium ion content was 8 ppm. This shows that the same effect can be expected even in the absence of sodium benzoate, and shows that the method of the present invention is an excellent method. Comparative Example 1 Same as Example 1 except that both the polyoxyethylene nonylphenyl formaldehyde condensate and sodium benzoate were completely absent in the step of purifying the polymer obtained by the polymerization of Example 1. Although the operation was repeated, the final polymer obtained had a low intrinsic viscosity value of 0.17, and the sodium
The ion content was still high at 570 ppm. Comparative Example 2 In the step of purifying the polymer obtained by polymerization in Example 1, except that the polyoxyethylene nonylphenyl formaldehyde condensate was not used,
When the same operation as in Example 1 was repeated, the intrinsic viscosity of the final polymer obtained was as high as 0.29, but the sodium ion content in this polymer was still 590 ppm, which was not satisfactory. Nakatsuta. Examples 3 to 13 and Comparative Example 3 418 g (4.1 mol) of lithium acetate dihydrate was used instead of sodium benzoate, and 1.8 g (0.01 mol) of 1,
While adding 2,4-trichlorobenzene, N-
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount of methylpyrrolidone was increased to 310 g.
The amount of distilled water during this period was 250 ml, the internal pressure at the end of polymerization was 9.6 Kg/cm ² , the yield and yield of pale gray-brown granular PPS was 394 g and 89%, and this PPS had an intrinsic viscosity value of was 0.34, and the sodium ion content was 860 ppm. Hereinafter, only Example 3 was carried out in the same manner as in Example 1, while Examples 4 to 13 were carried out in the same manner as in Example 1 except that the compounds and their usage amounts were changed as shown in Table 1. Example 3 was carried out in the same manner as Comparative Example 1. The results for each of those example cases are shown in Table 1.

【table】

Claims (1)

[Scope of Claims] 1 Polyphenylene sulfide containing impurities consisting of electrolyte components is mixed with at least one compound selected from the group of alkyl phenyl formaldehyde condensates represented by the following general formula A in an organic amide solvent. A method for purifying polyphenylene sulfide, the method comprising heating in the presence of a polyphenylene sulfide to reduce the content of the electrolyte component. General formula A: (In the formula, R ¹ is an alkylene group having 2 to 4 carbon atoms,
R ² is hydrogen or an alkyl group and/or an aryl group having 1 to 30 carbon atoms, and m and n indicate an average degree of polymerization, and represent 2 to 50 and 0 to 90, respectively. )